Method for manufacturing an engineered stone and an engineered stone

ABSTRACT

A method for manufacturing an engineered stone, the method including: providing a mixture comprising at least a stone or stone like material and a binder; compacting the mixture; curing the binder; and printing on at least a top surface of the engineered stone.

FIELD

The present disclosure relates to a method for manufacturing anengineered stone and an engineered stone.

BACKGROUND

An engineered stone includes a stone material or a stone like material,like for example crushed stones, sands or other minerals but alsorecycled ceramic, glass and metals, bonded by means of a cured binderlike for example resin or cement. More in detail, with engineered stoneis intended a composite material formed by a stone material or a stonelike material bonded together by means of a cured binder that it iscured at low temperature, wherein with low temperature is intended atemperature below 500° C.

Traditionally, natural stone is used as building material, especiallyfor finishing the buildings like for example for coverings of wall orfloor and for producing worktops like kitchen or bathroom countertopsand vanities. Natural stones are extracted from mines and subsequentlycut and polished to obtain slabs or boards of the desired shape. Due tothe mine extraction, natural stones are relatively expensive and producea high impact on the environment.

Therefore, in the past years methods for manufacturing engineered stoneswere developed in order to reduce costs and provide a more environmentfriendly product. A well-known example of such methods is represented bythe so called Bretonstone® technology described, for example, in thedocument, WO 2007/138529. Said document discloses a method formanufacturing an engineered stone which includes the step of: providinga stone material or a stone like material, for example by grinding sandor quartz; mixing the stone or stone like material with a binder, forexample a resin powder, in order to obtain a mixture; depositing themixture in a mold of a press, having shape and dimension similar tothose of the final article; press the mixture applying vacuum, with theaccompanying application of a vibratory motion at pre-establishedfrequency; the semi-product obtained is then hardened by means of a heatcuring process to obtain the engineered stone; the engineered stone isthen subjected to finishing steps like cutting or polishing.

Such kind of engineered stone normally includes a one-color decoration.Alternatively, the engineered stones include a décor includingartificial veins for imitating a natural stone like marble or granite.As disclosed in WO 2009/010406 such décor is obtained by adding acoloring agent to the mixture before the mixture is deposited in themold. The mixture is carried by an endless belt above the mold and isloaded into the mold itself by free falling from the end of the belt.The coloring agent is loaded by means of appropriate nozzles to thesurface of the mixture substantially in correspondence of the end of thebelt so to fall into the mold together with the mixture in anon-controlled manner. Following the vibro-compression step the pigmentparticles distribute in the mixture thereby generating a veined effectthrough the entire thickness of the engineered stone. Therefore, withthis technique it is not possible to obtain an engineered stone with areproducible and predefined décor.

WO 2016/113652 discloses an equipment and a method for creatingprogrammable chromatic effect in an engineered stone by means of acomputer controlled machine. The machine is an anthropomorphous robot ora cartesian robot provided with one or more nozzles for dispensing acoloring agent on the surface of a mixture in a temporary support. Thenozzle is connected to a tool that interacts with the surface of themixture to create grooves or holes to receive the color. Thus, thisequipment needs a machine work of the mixture and provides for décorimitating natural stone or woods with a relative low-quality resolution.

Certain embodiments of the present invention provide an alternativemethod for manufacturing an engineered stone, which, in accordance withseveral of its preferred embodiments, is directed to solve one or moreof the problems arising in the state of the art.

SUMMARY

Thereto, according to a first independent aspect, certain embodiments ofthe disclosed invention relate to a method for manufacturing anengineered stone, including the steps of:

-   -   providing a mixture including at least a stone or stone like        material and a binder;    -   compacting the mixture;    -   curing the binder;        and wherein the method includes the step of printing on at least        a top surface of the engineered stone. Preferably, inks are        printed on at least a top surface of the engineered stone.        Inventors have found that by means of printing step it is        possible to reproduce a wide variety of predetermined décor on        the engineered stone.

The engineered stone can be manufactured in any desired form althoughsubstantially flat shapes like a board, a tile or a slab are preferred.The engineered stone is preferably shaped as a slab wherein with slab isintended a substantial rectangular and flat form, preferably including asurface of minimum 1.5 square meters. In this way, the engineered stoneis manufactured in a shape that is sufficiently large to be versatileand adapted to be cut according to the dimension and shape of the finaldestination of the engineered stone itself, like for example a kitchenor bathroom countertops. According to a preferred embodiment, the slabhas a length of at least 2 m, preferably at least 2.5 m, for example 3 mor more, and a width of at least 1 m preferably 1.5 m or more. Moreover,the slab preferably shows a thickness of at least 10 mm, preferably atleast 20 mm for example 30 mm.

The stone or stone like material can include any kind of stone, sands,siliceous mineral material, for example quartz, silica sand, clay,feldspar cristobalite granite, talc or calcareous mineral material, forexample, calcium carbonate, marble, gypsum. The stone or stone likematerial can also include ceramic, glass, metals and other inorganicmaterial, for example recycled materials. The stone or stone likematerial can be in form of powder, granules, shards, grains, aggregatesor any other particulate form although granules and powder forms arepreferred. Preferably the stone or stone like material is in powder formhaving an average particle dimension lower than 45 μm, preferably lowerthan 20 μm. The stone or stone like material is preferably at least the80% by weight of the mixture, preferably more than the 85% and morepreferably more than 90%. According to another embodiment of theinvention the stone or stone like material can be in form of aggregates,grains and/or granules having a particles size distribution between 0.1and 0.7 mm. According to still another embodiment of the invention thestone or stone like material includes at least 60 wt % of grains and/orgranules and between 20 to 35 wt % of powder form wherein, for example,the granules have a particles size distribution between 0.1 and 0.7 mmand the powder have an average particle dimension lower than 45 μm,preferably lower than 20 μm.

The binder is a curable substance that is configured to be cured therebybonding together the particles of the stone or stone like material. Thebinder can be in any form, i.e. liquid, solid, gel or any form that issuitable to be mixed with the stone or stone like material and to behomogeneously dispersed within. Although any kind of curable substancecan be used, heat curable substances are preferred. The binder can be anorganic substance, for example a resin, or an inorganic substance, forexample a concrete.

In case the binder is an organic substance, it can be either athermoplastic or a thermosetting resin. For example, thermoplasticresins can be polyolefin resins like polyethylene or polypropylene,polystyrene or polyester like polyethylene terephthalate, whereasexamples of thermosetting resins are acrylic resin, epoxy resin,polyurethane, rubber, polyester resin preferably unsaturated polyesterresin, vinyl ester resin or the like. For example, in a preferredembodiment the binder is unsaturated polyester resin. The binder ispreferably less than the 20% by weight of the mixture, preferably lessthan the 15% and more preferably less than 10%.

In case the binder is an inorganic substance, it is preferably a cementfor example a portland cement. In this case the binder can be up to the30% by weight of the mixture and the stone or stone like material can bebetween 70% and 100% by weight.

It is noted that the mixture can also include additives, like forexample coupling agents, catalyst or reagents to activate or speed uphardening of the binder, and/or temporary bonding agent like glues orthermoplastic resins that temporarily bonds the stone or stone likematerial.

It is also noted mixture can include fillers, for example inorganicfillers like sand, quarts, feldspar, silica, calcium carbonate, moreparticularly in powder form, for example to reinforce the binder thatfills the interstices between the stone or stone like materialparticles. The fillers are preferably mixed to the binder, for examplethey are dispersed into the resin or the cement to form a binding pastor binder pellets destined to be mixed with the stone or stone likematerial for forming the mixture.

Moreover, reinforcing elements like, for example, fibers or whisker, canbe added to the mixture for reinforcing the engineered stone. Preferablyreinforcing elements include fiberglass, carbon fiber or metal fibers.

The mixture can be provided in different forms, for example in form of apasty material or a slip, although an incoherent particulate form ispreferred. According to a preferred embodiment wherein the mixture isprovided in form of an incoherent material, the mixture includes a firstparticulate of stone or stone like material and a second particulate ofbinder mixed together, preferably in powder form. Alternatively, theincoherent particulate can be formed by granulates or pellets whereineach granule includes the stone or stone like material and the binderbonded together for forming the granule. According to this alternative,the stone or stone like material and the binder can be bonded togetherby means of a temporary bonding agent like a glue or a thermoplasticresin, or the stone or stone like material and the binder can bemechanically or physically bonded together, for example the binder canbe a thermoplastic resin partially or fully coating the stone or stonelike material, or the stone or stone like material can be dispersed in asolidified thermoplastic resin, or the stone or stone like material andthe binder can be compressed together to form said granules.

It is noted that the mixture can be provided directly into a mold, aframe or any other tool suitable to providing a shape to the mixture bymeans of hopper or feeder, although it is preferred to provide themixture on a temporary support like for example a conveyor belt or atray so that it is possible to provides intermediate working step beforethe compacting phase, like for example machining of the edges of theslab or adding a coloring agent to the mixture.

A coloring agent can be added to the mixture to provide a basic color ofthe engineered stone. In this way, it is possible to provide abackground for the printed pattern like a white, grey, beige or brownbackground. Alternatively, the coloring agent can be added in such amanner to form a basic décor, e.g. a veined effect imitating the veinsor flakes of a marble, a granite or any natural stone. In this way, itis possible to combine the basic décor obtained by the coloring agentwith the printed pattern thereby obtaining more complex and pleasingaesthetic effects of the engineered stone. The coloring agent can beeither in liquid form or in powder form. The coloring agent can also beeither an inorganic or an organic substance.

In case the coloring agent is added to provide a basic color of theengineered stone, it can be dispersed in the mixture before it is loadedin the mold or in the frame or on the temporary support so that thecoloring agent colors the bulk of the engineered stone, i.e. the entirebody of the engineered stone is colored by the coloring agent.Alternatively, it is possible to provide the coloring agent so that itcolors only the surface of the engineered stone. For example, it ispossible to provide a coloring agent in order to coat at least partiallythe surface to be printed so to provide a background for the printedpattern. Such basic color can be obtained either with printingtechnique, for example a screen printing or a roller printing, or with acoating technique like for example spray technique.

In case the coloring agent is added to create a basic décor, it can beadded either after that the mixture is loaded in the mold, in the frameor on the temporary support or contemporary to the loading of themixture in the mold, in the frame or on the temporary support. In thefirst case, the coloring agent can be added by a computer controlledmachine, like for example an anthropomorphous robot or a cartesianrobot, provided with one or more nozzles for dispensing the coloringagent. The nozzle is connected to a tool that interacts with the surfaceof the mixture to create grooves or holes to receive the coloring agent.In the second case, the coloring agent can be randomly dispersed by freefalling from a feeder on the surface of the mixture together with themixture itself so that the veined effect is obtained in an uncontrolledmanner and every engineered stone is provided with a unique décor.According to said alternative embodiment of joining the coloring agent,the coloring agent is preferably distributed in the body of theengineered stone along lines imitating the veins or flakes of a marble,a granite or any natural stone. In both these cases, the basic décor iscreated in the entire thickness of the engineered stone so that it isvisible also form the lateral side of the engineered stone andpreferably from any section of the engineered stone itself. For example,the décor is visible also in the new sides generated from a cut createdin the engineered stone.

According to a preferred embodiment during the compacting step themixture is loaded in a mold, a frame or any other tool suitable forproviding a shape to the mixture of a press or compacting device.Preferably, the mold or frame can have the shape and dimension similarto those of the final product to be obtain or to those of a semi productof the process. Preferably the mold or frame has the shape and dimensionsimilar to those of a slab or a block. Preferably the compacting step isconducted under vacuum, i.e. vacuum is generated in the mold or frame tohelp extracting air between the mixture particles. More preferably,vibration is applied to the mold or frame during the pressing stepthereby helping to compact of the mixture particles, so that theporosity of the engineered stone is significantly reduced. According toa preferred embodiment both vacuum and vibration are applied to themixture during the compression.

It is not excluded that the engineered stone is formed according toalternative techniques different from compaction like casting, extrusionor lamination. For example, the mixture, in liquid or pasty form, can bepoured into the mold or extruded.

According to an embodiment of the invention the method may include thestep of forming a relief structure on the top surface of the engineeredstone, for example including protrusions and/or excavation. Preferablythe relief structure includes features related to the basic décor and orthe printed pattern, for example the relief structure includesprotrusions and/or excavations that run substantially parallel withrespect to the veins of the imitated natural stone. Preferably therelief structure is created by means of a structured mold during thecompacting step, although other techniques are available. For example,the relief structure can be created by means of embossing rollers, orembossed molds after or during the compacting step.

After the compacting step, the engineered stone is carried to a curingstation. The cure of the binder can be obtained by means of radiation,heat, chemical curing or other suitable techniques. In any case, thecuring step is conducted at a temperature below 500° C., for examplebelow 200° C., for example at room temperature.

In case the binder is a thermosetting resin, the curing step ispreferably a heating step because it provides for a homogeneous curingof the binder through the entire body of the engineered stone and it isrelatively cheap and easy to control. Preferably the heating step isconducted a temperature below 200° C., more preferably below 100° C.,for example at 90° C. During the heating step the binder cures andpermeates the interstices between the particles of stone or stone likematerial thereby bonding together the particles of stone or stone likematerial and reducing the porosity of the engineered stone.

In case the binder is a thermoplastic resin, the curing step isconducted by heating the mixture up at least around or above the Tg(glass transition temperature), preferably up to the melting temperatureof the thermoplastic resin so that the viscous or liquid resin permeatesthe interstices between the particles of stone or stone like material,and then cooling down the mixture to solidify the thermoplastic resin tobond together the particles of stone or stone like material and reducethe porosity of the engineered stone. The cooling step can be conductedeither at room temperature or in a forced manner for example by means ofbelt cooling or blowing air onto the engineered stone.

In case the binder is a cementitious material, the curing step is achemical curing wherein an activator like water or carbon dioxide isadded to the mixture to activate the hardening of the cement by means ofhydration or carbonation reaction.

The printing step can be conducted by means of a wide variety oftechniques, for example screen printing or roller printing althoughdigital printing is preferred. Digital printing, preferably inkjetdigital printing, allows to reproduce a wide variety of images with avery high resolution. For example, by means of digital printing it ispossible to obtain a printed pattern with a resolution up to 660 dpi.Moreover, digital printing is preferred above roller printing and screenprinting because it is a more flexible printing solution. For changingthe production from one décor to another décor it is not necessary tochange printing tools like the rollers or the screens.

It is noted that the printing step can be conducted either before orafter the curing step. According to a preferred aspect of the certainembodiments of the invention the step of printing is conducted beforethe step of curing. In this way, since the engineered stone is nothardened the ink can flow through the interstices between the particlesof stone or stone like material thereby penetrating into the thicknessof the engineered stone so that after the curing step the engineeredstone can be polished without deteriorate the printed pattern. More inparticular, the printing step can be conducted either before or afterthe compacting step. Preferably the printing step is conducted beforethe compacting step so that the subsequent compacting phase, preferablya vibro-compacting phase, helps the inks to penetrate through thesurface of the engineered stone. In this way, the printed pattern ispreferably present in a thickness of the compacted engineered stone,called penetration depth, of at least 0.5 mm starting from the topsurface, more preferably above 1 mm, for example above 2 mm so thatafter polishing of the top surface the digital printed pattern is stillvisible. In case the coloring agent is provided on the engineered stone,the printing step is conducted after the step of providing the coloringagent.

According to another embodiment of the invention, the printed patterncan be provided also on other surfaces of the engineered stone that aredifferent with respect to the top surface, preferably on the edges ofthe engineered stone i.e. on surfaces that are inclined or substantiallyperpendicular to the top surface of the engineered stone. In this case aprinting equipment with an orientable printing head can be used.Alternatively, multiple printing steps can be conducted, preferably in asequential order. For example, a first printing step provides for afirst printed pattern on the top surface, and a second printing stepprovides for a second printed pattern on the longitudinal and/or thetransversal edge.

According to a preferred embodiment the printed pattern on the edges areprovided after the curing step, more preferably after machining steplike calibration or machining.

It is noted that the printed pattern is preferably applied in a fixedrelationship to a predetermined point, such that the print is applied ata predetermined location of the of the slab, e.g. at a fixed distance,that may be zero, from an edge or corner, and that the printed patternis preferably aligned to an edge, preferably a longitudinal edge of theslab. Such can be obtained through a detection of the upcoming slab, andusing this detection to control the printer. Applying the printedpattern in a fixed relation to a predetermined point is advantageous forobtaining corresponding structural features in the relief. Furthermore,in case that the multiple printed patterns are provided on differentsurfaces of the engineered stone it is possible to match the differentprinted patterns together to form a single image or décoration thatcontinues from one surface to the other.

According to certain embodiments, either organic or inorganic inks or acombination of both can be used. For example, water based inks, solventbased ink, or sublimation in can be used. Since it is not necessary tofire the engineered stone at high temperature organic inks can be usedso that a wide gamut of color for the décor is obtainable. It is notedthat the organic ink can be a curable ink, for example a UV, IR curableink or heat curable ink, and that the method can include a print curingstep for curing the printed pattern, wherein the print curing step canbe either the same curing step of the engineered stone or a differentcuring step.

In case inorganic inks, for example ceramic inks, are used a durableprinted pattern is obtainable, wherein with durable is meant able toresist to physical and chemical agents like UV radiation, acid or basicattack. Preferably the inorganic inks include particles of pigmentshaving a maximum dimension below 2 μm, for example below 1.5 μm, so thatit is possible to obtain a printed pattern having a very highresolution. Moreover, the inventors have surprisingly found that usingpigments having a maximum dimension below 2 μm, for example below 1.5μm, the penetration depth of the printed pattern is significantlyincreased.

Moreover, the ink can show a viscosity below 70 cP, preferably below 50cP and/or a surface tension below 25 dyn/cm. The inventors havesurprisingly found using inks having low viscosity and/or surfacetension it is possible to increase the penetration depth of the ink.

It is noted that the printed pattern can be obtained by means ofmultiple color inks, for example with four colors, preferably cyan,magenta, yellow and black, or more colors, for example seven or eightcolors.

Furthermore, the method can include the step of providing at least thesurface to be printed with a primer, for example an ink adhesionpromoter or a catalyst, before the step of printing itself. The primercan be for example acrylic, methacrylic, polyurethane, water based,solvent based, styrene. The primer can be provided by means of spray,rollers or any other suitable techniques.

It is noted that the method can also include the step of providing aprotective layer to coat partially or entirely at least the top surfaceof the engineered stone. Preferably, the protective layer is providedabove the printed pattern, in this case it is preferable that theprotective layer is a transparent or translucent layer. The protectivelayer can be, for example, a curable resin like an acrylic or epoxyresin. The protective layer can also be configured to improvesuperficial properties of the engineered stone like for examplecleanability, impermeability, antimicrobial behavior, wear resistance,scratch resistance or the like. In order to improve such superficialproperties, the protective layer can include fillers, like corundum,silver, titanium dioxide, or others, dispersed therein to improve thesuperficial properties. The protective layer is preferably providedafter the printing step, preferably before the hardening step so that itis hardened together with the mixture and the print. According to analternative embodiment the protective layer is provided after the curingstep of the mixture and the method includes a second hardening stepconfigured to harden the protective layer. The protective layer isprovided by means of spray, rollers or any other suitable techniques.

It is clear that the method may also include the step of polishing atleast partially the surface of the slab, preferably at least the surfaceincluding the printed pattern. The polishing step it is advantageouslyconducted in order to remove an amount of material from the surface sothat the printed pattern is still visible on the polished surface. Forexample, the polishing step is performed in such a way to remove lessthan 2 mm of the thickness of the slab, preferably less than 1 mm, forexample 0.5 mm. In other words, the polishing step is performed in sucha way to reduce the thickness of the slab of an amount smaller than thepenetration depth.

Furthermore, the method can include further machining steps like forexample cutting, drilling, milling or grinding the engineered stone. Inparticular, the engineered stone can be cut according to the desiredshape and dimension following the specification of the customer design.For example, in case the engineered stone is used as a bathroom orkitchen countertop it can be cut to fit to the furniture on which itmust be fitted. Also, through holes can be provided in the engineeredstone to accommodate hob, a washbowl, sockets or other item.

Certain embodiments of the invention according to its second independentaspect provide for an engineered stone including a stone or stone likematerial and a binder bonding together the particles of stone or stonelike material wherein the engineered stone includes at least a topsurface having a printed pattern. The inventors have found that thanksto this solution an engineered stone with a wider range of décor can beobtained. Furthermore, a higher resolution and more realistic décor canbe obtained.

The printed pattern can represent any décor, design or inscription,although it is preferred that the printed pattern represents animitation of a natural stone, i.e. represents the veins and/or flakes ofa natural stone like a marble or a granite.

The engineered stone of the second aspect of the invention is preferablyobtained or obtainable through a method in accordance with the firstaspect of the invention or the preferred embodiments thereof. Theengineered stone may show one or more of the product features describedin connection with the first aspect, without necessarily beingmanufactured in accordance with the method of the first aspect.

Furthermore, certain embodiments of the invention according to its thirdindependent aspect provide for a countertop including an engineeredstone that includes at least a top surface having a printed pattern. Thecountertop can be used in a kitchen, a bathroom as well as any otherenvironment. The countertop preferably includes holes for accommodate ahob, a washbowl, a socket or any other item. The countertop of the thirdaspect preferably includes an engineered stone in accordance with theaforementioned second aspect and/or an engineered stone obtained orobtainable through a method in accordance with the first aspect of theinvention.

It is noted that the characteristic that the engineered stone includes aprotective layer forms an inventive idea irrespective of the presence ofa top surface including a décor and, in particular, irrespective of thetop surface including a printed pattern. Thus, according to a fourthindependent aspect, certain embodiments of the invention provide for anengineered stone including a stone or stone like material and a binderbonding together the stone or stone like material wherein the engineeredstone includes at least a top surface and wherein the engineered stoneincludes a protective layer to coat partially or entirely at least thetop surface.

It is clear that the engineered stone, as mentioned in all aspects ofthe invention, is not limited to the use as a countertop but it can beused as a floor element for floor covering, wall panels, internal orexternal cladding or panels for furniture and vanities as well.

With the intention of better showing the characteristics of theinvention, in the following, as an example without any limitativecharacter, several preferred embodiments are described with reference tothe accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an engineered stone in accordance withan example embodiment;

FIG. 2 shows the cross section along the line II-II indicated in FIG. 1;

FIG. 3 shows a view on the area F3 indicated on FIG. 2 ;

FIG. 4 shows a view on the area F3 indicated on FIG. 2 according to adifferent embodiment;

FIG. 5 shows some steps of a method in accordance with an exampleembodiment of the invention;

FIG. 6 shows some steps of a method in accordance with a variant of theinvention;

FIG. 7 shows some steps of a method in accordance with a further variantof the invention;

FIG. 8 shows some steps of a method in accordance with still anothervariant of the invention;

FIG. 9 on a larger scale shows a view on the area F3 indicated on FIG. 2before the engineered stone is polished;

FIG. 10 is a perspective view of a countertop including an engineeredstone in accordance with an example embodiment of the invention;

FIG. 11 is a view along direction F11 of FIG. 1 of the engineered stoneaccording to a still alternative embodiment;

FIG. 12 shows some steps of a method in accordance with a furthervariant of the invention for the manufacturing of the engineered stoneof FIG. 11 ;

FIG. 13 on a larger scale shows a view on the area F3 indicated on FIG.2 according to another different embodiment;

FIG. 14 on a larger scale shows a view on the area F14 indicated on FIG.13 ;

FIG. 15 shows some steps of a method in accordance with a furthervariant of the invention for the manufacturing of the engineered stoneof FIGS. 13 and 14 ;

DETAILED DESCRIPTION

Referring to FIG. 1 , it is shown an engineered stone 1 including astone or stone like material and a cured binder that bonds together theparticles of stone or stone like material. The engineered stone 1 ispreferably made in form of a slab 2 having a length X of at least 2 m,preferably at least 2.5 m, for example 3 m or more, and a width Y of atleast 1 m preferably 1.5 m or more. Moreover, the engineered stone showsa thickness Z of at least 10 mm, preferably at least 20 mm for example30 mm.

The engineered stone 1 includes at least a top surface 3 provided with aprinted pattern 4. The printed pattern 4 can represent any décor, designor inscription, although it is preferred that the printed pattern 4represents an imitation of a natural stone, i.e. represents the veinsand/or flakes of a natural stone like a marble or a granite.

According to a variant of the invention, the engineered stone 1 caninclude a basic décor 5 defining a background for the printed pattern 4.For example, the basic décor 5 represents an imitation of a naturalstone, i.e. represents the veins and/or flakes of a natural stone like amarble or a granite. In this case the printed pattern 4 above the basicdécor 5 can represent special feature or special effects of the imitatednatural stone. As shown from FIGS. 2 and 3 , the basic décor 5 ispreferably created on the entire thickness of the engineered stone 1 sothat it is visible also form the lateral side of the engineered stone 1and preferably from any section of the engineered stone 1 itself.

According to a preferred embodiment, the top surface 3 of the engineeredstone 1 is smooth, for example polished. FIG. 4 shows an alternativeembodiment wherein the top surface 3 include a relief structure 6, forexample including protrusions and/or excavations. Preferably the reliefstructure 6 includes features related to the basic décor 5 and/or theprinted pattern 4, for example the relief structure 6 includesprotrusions and/or excavations that runs substantially parallel withrespect to the veins of the imitated natural stone represented by thebasic décor 5 and/or the printed pattern 4.

FIG. 5 shows a method for manufacturing the engineered stone 1illustrated in FIGS. 1 to 4 . The method includes the step S1 ofproviding a mixture M including at least a stone or stone like materialand a binder.

The stone or stone like material can include any kind of stone, sands,siliceous mineral material, for example quartz, silica sand, clay,feldspar cristobalite granite, talc or calcareous mineral material, forexample, calcium carbonate, marble, gypsum. The stone or stone likematerial can also include ceramic, glass, metals and other inorganicmaterial, for example recycled materials. The stone or stone likematerial can be in form of powder, granules, shards or any otherparticulate form although powder form is preferred. Preferably the stoneor stone like material is in powder form having an average particledimension lower than 45 μm, preferably lower than 20 μm. The stone orstone like material is preferably at least the 80% by weight of themixture, preferably more than the 85% and more preferably more than 90%.According to another embodiment of the invention the stone or stone likematerial can be in form of aggregates, grains and/or granules having aparticles size distribution between 0.1 and 0.7 mm. According to stillanother embodiment of the invention the stone or stone like materialincludes at least 60 wt % of grains and/or granules having a particlessize distribution between 0.1 and 0.7 mm and between 20 to 35 wt % ofpowder form having an average particle dimension lower than 45 μm,preferably lower than 20 μm.

The binder is a curable substance that is configured to be cured therebybonding together the particles of the stone or stone like material. Thebinder can be in any form, i.e. liquid, solid, gel or any form that issuitable to be mixed with the stone or stone like material and to behomogeneously dispersed within. Preferably, the binder is in powder orpellet form. Although any kind of curable substance can be used, heatcurable substances are preferred. The binder can be an organicsubstance, for example a resin, or an inorganic substance, for example aconcrete or silica.

According to the preferred embodiments shown in FIGS. from 5 to 8, thebinder is a thermosetting resin like embodiment the binder is(polyester, polystyrene, acrylic or epoxy resin). The binder ispreferably less than the 20% by weight of the mixture, preferably lessthan the 15% and more preferably less than 10%.

The mixture M can also include additives, like for example catalyst orreagents to activate or speed up hardening of the binder, and/ortemporary bonding agent like glues or thermoplastic resins thattemporarily bonds the stone or stone like material.

Moreover, the mixture M can include fillers, for example inorganicfillers like sand, quarts, feldspar, silica, calcium carbonate in finepowder form to reinforce the binder that fills the interstices betweenthe stone or stone like material particles. The fillers are preferablymixed to the binder, for example they are dispersed into the resin orthe cement to form a binding past or binder pellets destined to be mixedwith the stone or stone like material for forming the mixture.

The components of the mixture M are mixed together and are provided on atemporary support 10 by means of a feeding device 11, for example ahopper. The temporary support 10 can be a mold, a frame, a tray or aconveyor, for example a conveyor having lateral containment means forproviding the mixture of a shape similar to that of the final slab. Inthe embodiment shown in FIG. 5 the temporary support 10 is in the formof a mold 12 carried by a first conveyor 13, for example a conveyorbelt, through the direction A.

According the preferred embodiment shown in the figures, the mixture Mis provided in form of an incoherent particulate, and includes a firstparticulate of stone or stone like material and a second particulate ofbinder mixed together, preferably in powder form for example into thefeeding device 11.

The method can further include the step of forming the basic décor 5 onthe engineered stone 1. In the embodiment shown FIG. 5 a computercontrolled machine 14, for example an anthropomorphous robot candistribute a coloring agent on the engineered stone. According to apreferred embodiment the computer controlled machine is provided with anozzle for delivering the coloring agent that is connected to a tool,like a knife or a mill, that is configured for forming grooves orrecess, into the mixture M inside the temporary support 10, adapted toreceive the coloring agent. Thus, the computer controlled machine 14 cancreate colored lines or spots for example defining the veins of anatural stone following a predetermined input received from a computer.

FIG. 6 shows an alternative embodiment of adding the coloring agent,wherein the coloring agent is provided by free falling from a coloringagent feeder 15 feeder onto the mixture M. More in detail, the mixture Mis firstly fed on a temporary conveyor 16 placed substantially above thetemporary support 10 so that it can free fall on the temporary supportfrom an end of the temporary conveyor 16. The coloring agent is fed fromthe coloring agent feeder 15 onto the top surface of the mixture Msubstantially in correspondence of the end of the temporary conveyor 16so that the mixture and the coloring agent contemporary free fall on thetemporary support 10 and the coloring agent is randomly dispersed intothe mixture M.

Referring back to FIG. 5 , the method includes the step S2 of printingthe printed pattern 4 onto the top surface of the engineered stone 1,preferably by printing an ink. In the example, the temporary support 10conveyed by the first conveyor 13 is conveyed to a printing station 20provided with a printing device 21. According to the preferredembodiment shown in FIG. 5 the printing device 21 is a digital printer,preferably an inkjet digital printer.

For example, the printing device 21 is an inkjet digital printerincluding a printing head adapted to print with four or more colors.More in detail, the printed pattern 4 can be obtained by means ofmultiple color inks, for example with four colors, preferably cyan,magenta, yellow and black, or more colors, for example seven or eightcolors.

According to the preferred embodiment organic inks are used forproviding the printed pattern 4 on the engineered stone 1. Preferablythe inks are curable inks, for example UV, IR or heat curable inks.

The method further includes the step S3 of compacting the mixture M.according to the embodiment shown in FIG. 5 , the mold 12 conveyed tothe first conveyor 13 is moved to a compacting station 30 including apress 31 configured to apply a pressure to the Mixture M into the mold12. In the present embodiment, the mold 12 is the same used as temporarysupport 10 but it is clear that according to different embodiment themold 12 used in the press 31 can be different from the temporary support10.

Preferably the compacting station 30 includes also a vibrating unit 32configured to apply a vibration to the mixture during the compactingstep S3. Moreover, according to the preferred embodiment, the compactingstation 30 includes also a vacuum unit 33 configured to create vacuuminto the mold 12 during the compacting step S3.

In the embodiment shown in FIG. 5 , with reference to FIG. 9 also, thevibration applied to the mixture M during the compacting step S3 helpsthe ink of the printed pattern 4 to permeates the mixture M so topenetrate through the top surface 3 of the slab for a penetration depthP of at least 0.5 mm starting from the top surface, more preferably of 1mm, for example of 2 mm.

The method further includes a curing step S4 for curing the binder ofthe mixture M thereby bonding together the stone or stone like materialsand, thus, obtaining the slab 2 of engineered stone 1. According to theembodiment shown in FIG. 5 the compacted mixture is moved from thecompacting station 30 to a second conveyor 34 that conveys the compactedmixture M to a curing station 40.

According to the preferred embodiment, the curing station 40 includes aheating device 41 configured to heat curing the mixture M, i.e. it isconfigured to heat the mixture M up to the curing temperature of thebinder. Preferably the heating temperature is below 200° C., morepreferably below 100°, for example 90° C.

The method, according to certain embodiments of the invention, canfurther include one or more machining steps S5, for example a polishingstep. According to the preferred embodiment shown in the FIGS. theengineered stone is moved by the second conveyor 34 to a machiningstation 50 including a polishing device 51. The polishing device 51 isconfigured to polish the top surface 3 of the slab 2. Preferably thepolishing step S5 is conducted in such a way to remove a very limitedamount of material from the top surface 3 of the slab, and in particularit is conducted in such a way that after the polishing step the printedpattern 4 is visible from the top surface 3 of the slab 2. For example,the polishing step S5 is conducted in such a way to remove less thanless than 2 mm of the thickness of the slab, preferably less than 1 mm,for example 0.5 mm, i.e. less than the penetration depth P from the topsurface 3.

The method can include further machining steps S5, like for examplecutting, drilling or milling step. For example, the machining station 50can include a cutting device for cut the slab 2 according to the shapeand dimension of the design of the desired final use of the engineeredstone 1.

For example, FIG. 10 shows a countertop 80 including the engineeredstone 1, for example made starting from the slab 2, that includesthrough holes 81 for accommodate a hob, a washtub, a socket or any otheritem.

FIG. 7 shows a different embodiment of the method wherein the printingstep S2 is conducted after the compacting step S3 and before the curingstep S4. In this case the ink printed pattern 4 can still permeate themixture through the interstices between the particles of stone or stonelike material since the binder is not yet cured.

FIG. 8 shows a further embodiment, wherein the printing step S2 isconducted after the heating step S4. In this case, the method caninclude a print curing step S6 for curing the printed pattern on thealready cured engineered stone 1. For example, the engineered stone 1 isconveyed by the second conveyor 33 from the curing station 40 to theprinting station 20 and from the printing station 20 that includes aprint curing device 22.

FIG. 11 shows a further embodiment of the invention wherein the slab 2includes edges 7 provided with the printed pattern 4. FIG. 12 shows amethod for forming the slab 2 of FIG. 9 wherein subsequent printingsteps S2, S2′, S″ are conducted in a sequential order and wherein eachprinting step S2, S2′, S2″ for printing on a different surface withrespect to the others printing steps. According to this embodiment theprinting station 20 can include a plurality of printing devices 21wherein each printing device 21 is configured to print on a differentsurface.

FIG. 13 shows an embodiment of the invention wherein the engineeredstone 1 includes a protective layer 8 coating partially or entirely atleast the top surface 3 of the engineered stone 1. In the embodimentshown the protective layer 8 is provided above the printed pattern 4 andit is preferable a transparent or translucent layer. For example, theprotective layer 8 is a curable resin like an acrylic or epoxy resin.

As visible in FIG. 14 , the protective layer 8 advantageously includesfillers 9, like corundum, silver, titanium dioxide, or others, dispersedtherein to improve the superficial properties of the engineered stone 1like for example wear and scratch resistance and antimicrobial behavior.

FIG. 14 shows a method for forming the engineered stone 1 of FIG. 13that, subsequent printing steps S2, includes the step S7 of providingthe protective layer 8 above the printed pattern 4. In the example shownin FIG. 12 the coating step S7 is conducted before the curing step S4 sothat the protective layer 8 is cured together with the ink and theengineered stone 1. According to said embodiment the engineered stone 1is conducted from the printing station 20 to a coating station 70provided with at least a coating device 71, for example a roller or asprayer, configured to provide the protective layer 8 above the printedpattern 4, subsequently the compacted mixture is carried to the curingstation S4 to be cured.

The present invention is in no way limited to the hereinabove describedembodiments, but such floor, floor covering and floor elements may berealized according to different variants without leaving the scope ofthe present invention.

Further, as is clear from the content of the description, the certainembodiments of the present invention relates to one or more of the itemsas listed below, numbered from 1 to 21:

1.—A method for manufacturing an engineered stone (1) including the stepof:

-   -   providing (S1) a mixture (M) including at least a stone or stone        like material and a binder;    -   compacting (S3) the mixture (M);    -   curing (S4) the binder;

and wherein the method includes the step of printing (S2) on at least atop surface (3) of the engineered stone (1).

2.—The method in accordance to item 1, wherein the printing step (S2) isa digital printing step.

3.—The method in accordance to item 2, wherein the printing step (S2) isan inkjet digital printing step.

4.—The method in accordance to any of the previous items, wherein theprinting step (S2) is conducted before the curing step (S4).

5.—The method in accordance to any of the previous items, wherein theprinting step (S2) is conducted before the compacting step (S3).

6.—The method in accordance to any of the previous items, wherein themixture (M) is provided on a temporary support (10) and the printedpattern (4) is provided on a top surface (3) of the mixture (M) on thetemporary support (10).

7.—The method in accordance to any of the previous items, wherein theprinted pattern (4) is formed with at least an organic ink.

8.—The method in accordance to any of the previous items, wherein theprinted pattern (4) is formed with at least an inorganic ink.

9.—The method in accordance to any of the previous items, wherein itincludes the step of adding a coloring agent to the mixture (M) toprovide a basic color.

10.—The method in accordance to any of the previous items, wherein itincludes the step of adding a coloring agent to the mixture (M) in sucha manner to provide a basic décor (5).

11.—The method in accordance to item 10, wherein the basic décor (5) isa veined effect imitating a natural stone.

12.—The method in accordance to any of the previous items, wherein itincludes a further step of printing a printed pattern (4) on a surface(8) that is different with respect to the top surface (3) of theengineered stone (1).

13.—An engineered stone (1) including a stone or stone like material anda binder bonding together the stone or stone like material wherein itincludes at least a top surface (3) having a printed pattern (4).

14.—The engineered stone (1) in accordance to item 13, wherein theprinted pattern (4) is a digital printed pattern.

15.—The engineered stone (1) in accordance to any of items 13 or 14,wherein it further includes a basic décor (5).

16.—The engineered stone (1) in accordance to item 15, wherein the basicdécor (5) is present in to the entire thickness of the engineered stone.

17.—The engineered stone (1) in accordance to any of items from 13 to15, wherein it includes a further surface (8) different with respect tothe top surface (3) and wherein the further surface (8) is provided withthe printed pattern (4).

18.—The engineered stone (1) in accordance to any of items from 13 to16, wherein the engineered stone (1) is in form of a slab (2).

19.—The engineered stone (1) in accordance to item 18, wherein the slab(2) has a width (Y) of at least 1 mm and a length (X) of at least 2 m.

20.—The engineered stone (1) in accordance to item 18 or 17, wherein theslab (2) has a thickness (Z) of at least 10 mm.

21.—A countertop (80) including an engineered stone (1) and including atleast a top surface (3) having a printed pattern (4).

In the present description, numerous specific details are set forth.However, it is to be understood that embodiments of the disclosedtechnology may be practiced without these specific details. In otherinstances, well-known methods, structures, and techniques have not beenshown in detail in order not to obscure an understanding of thisdescription. References to “one embodiment,” “an embodiment,” “exampleembodiment,” “some embodiments,” “certain embodiments,” “variousembodiments,” etc., indicate that the embodiment(s) of the disclosedtechnology so described may include a particular feature, structure, orcharacteristic, but not every embodiment necessarily includes theparticular feature, structure, or characteristic. Further, repeated useof the phrase “in one embodiment” does not necessarily refer to the sameembodiment, although it may.

Unless otherwise noted, the terms used herein are to be understoodaccording to conventional usage by those of ordinary skill in therelevant art. In addition to any definitions of terms provided below, itis to be understood that as used in the specification and in the claims,“a” or “an” can mean one or more, depending upon the context in which itis used. Throughout the specification and the claims, the followingterms take at least the meanings explicitly associated herein, unlessthe context clearly dictates otherwise. The term “or” is intended tomean an inclusive “or.” Further, the terms “a,” “an,” and “the” areintended to mean one or more unless specified otherwise or clear fromthe context to be directed to a singular form.

Unless otherwise specified, the use of the ordinal adjectives “first,”“second,” “third,” etc., to describe a common object, merely indicatethat different instances of like objects are being referred to, and arenot intended to imply that the objects so described must be in a givensequence, either temporally, spatially, in ranking, or in any othermanner.

Also, in describing example embodiments, certain terminology is used forthe sake of clarity. It is intended that each term contemplates itsbroadest meaning as understood by those skilled in the art and includesall technical equivalents that operate in a similar manner to accomplisha similar purpose.

While certain embodiments of the disclosed technology have beendescribed, it is to be understood that the disclosed technology is notto be limited to the disclosed example embodiments, but covers variousmodifications and equivalent arrangements included within the scope ofthe appended claims. Although specific terms are employed herein, theyare used in a generic and descriptive sense only and not for purposes oflimitation.

This written description uses examples to disclose certain embodimentsof the disclosed technology, including the best mode, and to enable anyperson skilled in the art to practice the disclosed technology,including making and using any devices or systems and performing anyincorporated methods. The patentable scope may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elements asthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.

What is claimed is:
 1. A method for manufacturing an engineered stone,the method comprising: providing a mixture comprising at least aparticulate material and a binder; adding a coloring agent to themixture in such a manner to provide a basic décor; compacting themixture; curing the binder to form an engineered stone; polishing a topsurface of the cured engineered stone; printing a pattern with at leastone ultraviolet (UV) curable inorganic ink on the top surface of thecured engineered stone, the printed pattern having a resolution up to600 dots per inch (dpi); and curing the printed pattern, wherein theprinting is an inkjet digital printing step comprising applying aplurality of dots of ink to the top surface of the cured engineeredstone, wherein the basic décor is a veined effect imitating a naturalstone, wherein the basic décor is created on the entire thickness of theengineered stone, wherein the basic décor and the printed pattern areboth visible on at least the top surface of the cured engineered stone,wherein the basic décor is created before the compacting step, andwherein the printing step is performed after the compacting step.
 2. Themethod according to claim 1, further comprising adding a coloring agentto the mixture to provide a basic color.
 3. The method according toclaim 1, wherein the basic décor defines a background for the printedpattern.
 4. The method according to claim 1 further comprising providinga primer on at least the surface to be printed before the printing step.5. The method according to claim 1 further comprising providing aprotective layer to partially or entirely coat at least the top surfaceof the cured engineered stone.
 6. The method according to claim 5,wherein the protective layer is a transparent or translucent layer andis provided above the printed pattern.
 7. The method according to claim6, wherein the protective layer comprises a cured resin.
 8. The methodaccording to claim 7, wherein the cured resin comprises an acrylic orepoxy resin.
 9. The method according to claim 5, wherein the step ofproviding the protective layer comprises dispensing a curable resin andcuring the curable resin so as to form the protective layer.
 10. Themethod according to claim 1, wherein the printed pattern comprises animitation of a natural stone.
 11. The method according to claim 10,wherein the printed pattern comprises an imitation of veins and/orflakes of a natural stone.
 12. The method according to claim 1, furthercomprising printing a printed pattern on a second surface of the curedengineered stone that is different than the top surface of the curedengineered stone.